(19)

(11)

EP 0 428 515 A1

(12)

(43) Date of publication: 29.05.1991 Bulletin 1991/22 (21) Application number: 89904155.0 (22) Date of filing: 09.03.1989

(51) International Patent Classification (IPC):  E21B 33/ 038( . ) H01R 13/ 523( . ) (86) International application number: PCT/GB1989/000234 (87) International publication number: WO 1989/008934 (21.09.1989 Gazette 1989/23)

(84) Designated Contracting States: DE GB (30) Priority: 09.03.1988 GB 19880005601 (71) Applicant: ALPHA THAMES ENGINEERING LIMITED Essex RM14 2SU (GB)	(72) Inventor: WEBB, Alan, David Tonbridge Kent TN1Z 9AY (GB) (74) Representative: Murgatroyd, Susan Elizabeth, et al  Baron & Warren 18 South End Kensington London W8 5BU London W8 5BU (GB)